This invention relates to the field of FETs having improved higher frequencies and larger gain-bandwidth capabilities. More particularly inversion mode operation between heterojunction contacts through a p-type ternary alloy epilayer permits faster electron transit.
The only inversion mode field-effect transistors, other than silicon devices, are those employing indium phosphide or such as described by H. H. Wieder et al in IEEE Electron Device Letters, Vol. EDL-2, page 73 (1981) which are the basis of this invention.
The above cited related invention of H. H. Wieder represents still another advance in the state-of-the-art for improving the capability of the field-effect transistor. It discloses the use of p-type Ga.sub.0.47 In.sub.0.53 As in an epilayer under an insulated gate electrode and touching the source and drain contacts to help assure improved operational capabilities.
Although U.S. Pat. No. 3,982,261 to George A. Antypas discloses a quarternary alloy layer lattice-matched to an InP substrate, his application has been used for improving the responses of photocathodes and lasers. The energy bandgap differences are utilized to enhance the infrared sensitivity and to provide means for varying the operating wavelengths of a solid state laser. Antypas does not appreciate the favorable properties of the disclosed materials for use in a heterojunction field-effect transistor.
The disclosure of the U.S. Pat. No. 4,186,407 concerns the use of Ga.sub.0.47 In.sub.0.53 As to fabricate avalanche diodes intended to function as oscillators. The purpose and intent of this patent also is distinct from that of using heterojunction source and drain contacts and an insulated gate electrode for assuring improved operational characteristics of a field-effect transistor.
Thus, there is a continuing need in the state-of-the-art for a heterojunction source-drain insulated gate field-effect transistor in which lattice-matching materials are advantageously employed for the source and drain contacts to assure improved operational capabilities.